diff --git a/tests/gateway/test_queued_native_image_session_key.py b/tests/gateway/test_queued_native_image_session_key.py
index 86ba1620ade..e2489756157 100644
--- a/tests/gateway/test_queued_native_image_session_key.py
+++ b/tests/gateway/test_queued_native_image_session_key.py
@@ -86,7 +86,7 @@ def _make_runner(adapter):
     )
     runner._model = "openai/gpt-4.1-mini"
     runner._base_url = None
-    runner._decide_image_input_mode = lambda: "native"
+    runner._decide_image_input_mode = lambda **_kw: "native"
     return runner